The poly bushings that I used some time ago squeaked all of the time. The newer ones come with grease fittings and some are graphite impregenated. I'm sure thay have better now than when I used them some 15 years ago. I'm still a huge fan of the delalum bushings. Like I mentioned before they were torqued to inch pounds and you could move them up and down with your fingers. It was one of the best improvements that I did on the car.